I asked the same question of our local Dodge dealer and was given the same answer. They can flash a new FCM but cannot re-flash a used FCM. I wrote down the part number on the side of my old one from my 2006 Dakota and went shopping online by that part number only. I found and purchased one on EBay, plugged it in and it worked. The only difference I noticed is that when I first bought the truck, I followed directions to turn off the horn honk that happens when you lock the truck with the key FOB. After I changed the FCM, the honk returned, so I suppose that feature is programmed into the FCM. If you can find one with the exact same part number as your original, it will work, unless it's faulty. I don't know if this applies to a Dodge Durango.